Roadmap on thermoelectricity

The increasing energy demand and the ever more pressing need for clean technologies of energy conversion pose one of the most urgent and complicated issues of our age. Thermoelectricity, namely the direct conversion of waste heat into electricity, is a promising technique based on a long-standing physical phenomenon, which still has not fully developed its potential, mainly due to the low efficiency of the process. In order to improve the thermoelectric performance, a huge effort is being made by physicists, materials scientists and engineers, with the primary aims of better understanding the fundamental issues ruling the improvement of the thermoelectric figure of merit, and finally building the most efficient thermoelectric devices. In this Roadmap an overview is given about the most recent experimental and computational results obtained within the Italian research community on the optimization of composition and morphology of some thermoelectric materials, as well as on the design of thermoelectric and hybrid thermoelectric/photovoltaic devices

Ethylene photo-oxidation on copper phthalocyanine sensitized TiO 2 films under solar radiation

none6siLimited solar photo-activity and recovering the catalysts after photocatalysis reaction are two major drawbacks of the highly active TiO2 powder materials. In this study we propose that copper phthalocyanine (CuPc, Cu(II) tetrakis[4-(2,4-bis-(1,1-dimethylpropyl)phenoxy)]phthalocyanine), which is an metal-organic dye could be used as sensitizer of TiO2 coating to shift the absorption band toward visible light. TiO2 coating was applied inside the Pyrex glass tubes and used in the photocatalytic decomposition of ethylene gas under solar light irradiation. Two-step draining method was employed to apply the coating on the inner side of the glass tubes. At first pure TiO2 coating was prepared from a solution by dispersing the commercial P25 TiO2 powders in a TiO2 sol made by hydrolysis-condensation of titanium alkoxide. A controlled draining method was employed to coat the inner side of the glass tubes. After calcination at 500 °C, P25 powders were strongly attached on the glass surface as a thick coating. Visible light absorptive coating was prepared by applying a thin layer of CuPc that shows intense absorption in the visible wavelength region utilizing the same coating procedure. CuPc coated TiO2 film showed excellent photo-stability against solar radiation. Greater photo-oxidation rate of ethylene was achieved with the CuPcTiO2 coated glass tube compared to that without CuPc coating due to the enhanced solar light absorption.Licciulli, Antonio; Riccardis, Alberto De; Pal, Sudipto; Nisi, Rossella; Mele, Giuseppe; Cannoletta, DonatoLicciulli, ANTONIO ALESSANDRO; Riccardis, Alberto De; Pal, Sudipto Kumar; Nisi, Rossella; Mele, Giuseppe Agostino; Cannoletta, Donato Pompili

Turning lipophilic phthalocyanines/TiO2 composites into efficient photocatalysts for the conversion of CO2 into formic acid under UV–vis light irradiation

Metal-free, Cu(II)- or Zn(II) tetrakis [4-(2,4-bis-(1,1-dimethylpropyl)phenoxy)]phthalocyanines loaded over TiO2 (anatase) proved to be active in the photoreduction of CO2 to formic acid (HCO2H) in water under UV–vis light. CuPc/TiO2 is catalyst of choice, allowing to reach a maximum yield of HCO2H, unequalled by any other similar catalytic systems. Because of their low environmental impact, low potential cost, and efficient power conversion, these multipurpose materials show promise in the setup of sustainable methods for CO2 valorization

Turning lipophilic phthalocyanines/TiO2 composites into efficient photocatalysts for the conversion of CO2 into formic acid under UV-vis light irradiation

Metal-free, Cu(II)- or Zn(II) tetrakis [4-(2,4-bis-(1,1-dimethylpropyl)phenoxy)]phthalocyanines loaded over TiO2 (anatase) proved to be active in the photoreduction of CO2 to formic acid (HCO2H) in water under UV-vis light. CuPc/TiO2 is catalyst of choice, allowing to reach a maximum yield of HCO2H, unequalled by any other similar catalytic systems. Because of their low environmental impact, low potential cost, and efficient power conversion, these multipurpose materials show promise in the setup of sustainable methods for CO2 valorization. (C) 2014 Elsevier B.V. All rights reserve

Influence of newly synthesized titanium phosphates on the corrosion protection properties of alkyd coating

This study reports the effect of three new titanium phosphates Li0.5M0.25Ti2(PO4)3 (where M = Mn, Co and Ni) on the protective properties of alkyd resin films applied on carbon steel substrate in 3.5% sodium chloride solution. The performance of the coatings was evaluated by electrochemical impedance spectroscopy, oxygen and water permeability and pull-off adhesion measurements. It was found that titanium phosphates improve the corrosion resistance as well as the adhesion strength of alkyd resin coatings. The incorporation of titanium phosphates into the alkyd resin coating significantly enhances the pore resistance of the alkyd resin and decreases the coating capacitance. Lower water and oxygen permeability were observed for alkyd resin containing titanium phosphates, confirming formation of a protective layer on the surface. The order of anticorrosion performance of the three coatings was as follows: Li0.5Mn0.25Ti2(PO4)3 > Li0.5Co0.25Ti2(PO4)3 > Li0.5Ni0.25Ti2(PO4)3

Photoreduction of carbon dioxide to formic acid in aqueous suspension: a comparison between phthalocyanine/TiO2 and porphyrin/TiO2 catalysed processes

Composite materials prepared by loading polycrystalline TiO2 powders with lipophilic highly branched Cu(II)- and metal-free phthalocyanines or porphyrins, which have been used in the past as photocatalysts for photodegradative processes, have been successfully tested for the efficient photoreduction of carbon dioxide in aqueous suspension affording significant amounts of formic acid. The results indicated that the presence of the sensitizers is beneficial for the photoactivity, confirming the important role of Cu(II) co-ordinated in the middle of the macrocycles. A comparison between Cu(II) phthalocyanines and Cu(II) porphyrins indicated that the Cu(II)- phthalocyanine sensitizer was more efficient in the photoreduction of CO2 to formic acid, probably due to its favorable reduction potential

Impact of different TiO2 samples and porphyrin substituents on the photocatalytic performance of TiO2@copper porphyrin composites

In this manuscript, the preparation and the comparison of the photocatalytic activity of novel TiO2@copper porphyrin composites obtained by impregnation of (5-(4-hydroxy) phenyl-10,15,20-triphenyl copper porphyrin 1a, 5-(4-ethylacetatatomethoxy) phenyl-10,15,20-triphenylcopper porphyrin 1b, and 5-(4-carboxylatomethoxy) phenyl-10,15,20-triphenyl copper porphyrin 1c respectively onto the surface of different TiO2 samples, commercial (cTiO2) and home-prepared (pTiO2), has been reported. The TiO2@copper porphyrin composites were characterized by XRD, BET, UV–vis, FT-IR and SEM-EDS techniques. For the first time, the formation of aggregated porphyrin, most likely in form of dimers 1a-1a, 1b-1b and 1c-1c, were detected on the lower and less hydroxylated surface area of cTiO2. The photocatalytic activity of the samples was evaluated on the basis of the photodegradation of 4-nitrophenol (4-NP) in aqueous solution under metal halide lamp irradiation. The highest photocatalytic efficiency in the degradation of 4-NP, observed by using the carboxylporphyrin 1c as sensitizer supported onto the surface of both pTiO2 or cTiO2, was ascribed to the optimal combination of the anchoring mode with the efficient electron injection in the conduction band that carboxylic group produced at the surface of the TiO2 samples

Aluminum Metal–Organic Framework Triggers Carbon Dioxide Reduction Activity

Confinement of metal centers is a powerful tool to manipulate reactivity and tune selectivity in chemical transformations. While aluminum as a foil is inactive for carbon dioxide reduction and shows high selectivity for the hydrogen evolution reaction, here we show that aluminum confined in a metal-organic framework (MOF), MIL-53(Al), suppresses hydrogen evolution reaction activity and enhances carbon dioxide reduction. This aluminum MOF can produce up to 40% faradaic efficiency for carbon monoxide and formic acid. This study demonstrates that the unique reaction environment created by the MOF enables changes in reaction selectivity and can impart atypical catalytic capabilities to metals

Iminosugar-Cyclopeptoid Conjugates Raise Multivalent Effect in Glycosidase Inhibition at Unprecedented High Levels

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